Healthy pregnancy (18)
- Pregnancy nutrition: Healthy-eating basics
- Twin pregnancy: What multiples mean for mom
- Childbirth classes: Get ready for labor and delivery
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First trimester (7)
- Fetal development: The first trimester
- Prenatal care: First-trimester visits
- First trimester pregnancy: What to expect
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Second trimester (7)
- Second trimester pregnancy: What to expect
- Prenatal care: Second-trimester visits
- Fetal development: The second trimester
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Third trimester (9)
- Overdue pregnancy: What to do when baby's overdue
- Third trimester pregnancy: What to expect
- Fetal development: The third trimester
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Pregnancy problems (16)
- Bed rest during pregnancy: Get the facts
- Heart conditions and pregnancy: Know the risks
- High blood pressure and pregnancy: Know the facts
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Fetal development: The second trimester
Week 20: The halfway point
Halfway into your pregnancy, or 18 weeks after conception, you might be able to feel your baby's first movements, also known as quickening.
By now your baby might be about 6 1/3 inches (160 millimeters) long from crown to rump.
Week 21: Baby can swallow
Twenty-one weeks into your pregnancy, or 19 weeks after conception, your baby is poised to gain more weight. By this week your baby is becoming more active and might be able to swallow.
Week 22: Baby's hair becomes visible
Twenty-two weeks into your pregnancy, or 20 weeks after conception, your baby is completely covered with a fine, down-like hair called lanugo. The lanugo helps hold the vernix caseosa on the skin. Your baby's eyebrows might be visible.
By now your baby might be 7 1/2 inches (190 millimeters) long from crown to rump and weigh 1 pound (460 grams).
Week 23: Fingerprints and footprints form
Twenty-three weeks into your pregnancy, or 21 weeks after conception, your baby's skin is wrinkled, more translucent than before and pink to red in color.
This week your baby begins to have rapid eye movements. Your baby's tongue will soon develop taste buds. Fingerprints and footprints are forming. For boys, the testes are descending from the abdomen. For girls, the uterus and ovaries are in place — complete with a lifetime supply of eggs.
With intensive medical care, some babies born this week might be able to survive.
Week 24: Real hair grows
Twenty-four weeks into your pregnancy, or 22 weeks after conception, your baby is regularly sleeping and waking. Real hair is growing on his or her head.
By now your baby might be about 8 inches (210 millimeters) long from crown to rump and weigh more than 1 1/3 pounds (630 grams).
Week 25: Baby responds to your voice
Twenty-five weeks into your pregnancy, or 23 weeks after conception, your baby's hands and startle reflex are developing. Your baby might be able to respond to familiar sounds, such as your voice, with movement.
Week 26: Baby's fingernails develop
Twenty-six weeks into your pregnancy, or 24 weeks after conception, your baby has fingernails.
Your baby's lungs are beginning to produce surfactant, the substance that allows the air sacs in the lungs to inflate — and keeps them from collapsing and sticking together when they deflate.
By now your baby might be 9 inches (230 millimeters) long from crown to rump and weigh nearly 2 pounds (820 grams).
Week 27: Second trimester ends
This week marks the end of the second trimester. At 27 weeks, or 25 weeks after conception, your baby's lungs and nervous system are continuing to mature — and he or she has likely been growing like a weed. Your baby's crown-to-rump length might have tripled since the 12-week mark.
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- Healthy pregnancy: Stages of pregnancy. U.S. Department of Health and Human Services. http://www.4women.gov/pregnancy/you-are-pregnant/stages-of-pregnancy.cfm#second. Accessed March 31, 2011.
- Moore KL, et al. The Developing Human: Clinically Oriented Embryology. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2003:4.
- DeUgarte CM, et al. Embryology of the urogenital system and congenital anomalies of the female genital tract: Introduction. In: DeCherney AH, et al. Current Diagnosis & Treatment Obstetrics & Gynecology. 10th ed. New York, N.Y.: The McGraw-Hill Companies; 2007. http://www.accessmedicine.com/content.aspx?aID=2382989. Accessed March 31, 2011.
- American College of Obstetricians and Gynecologists. Your Pregnancy and Childbirth Month to Month. 5th ed. Washington, D.C.: American College of Obstetricians and Gynecologists; 2010:41.
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